Apparatus and process for applying discrete portions of a web material onto receiving web

ABSTRACT

The present invention relates to an apparatus for applying discrete portions ( 10 ) of a web material onto a receiving web ( 7 ) comprising: a primary axis of rotation and an attachment zone to an average radial distance, R 1 , from the primary axis of rotation; transfer elements ( 6 ) rotatable about the axis, the transfer elements receiving a second web ( 2 ) at a radial distance, R 2 , from the primary axis wherein the radial distance R 1 , is greater than the radial distance R 2 ; a means for displacing the transfer elements ( 6 ) so that the second web ( 2 ) is moved immediately adjacent to the attachment zone; and an attachment surface ( 10 ) rotatable about the primary axis and through the attachment zone, for transporting the receiving web ( 7 ) about the primary axis, whereby discrete portions ( 10 ) of the second web ( 2 ) are attached to the receiving web ( 7 ) in the attachment zone, forming a composite web comprising the receiving web ( 7 ) and discrete portions ( 10 ) of the second web ( 2 ). The present invention also relates to a process for applying discrete portions ( 10 ) of a web material onto a receiving web ( 7 ) using the above described apparatus.

The present invention relates to an apparatus and a process for applyingdiscrete portions of a web material onto a receiving web. The apparatusand process are particularly useful in the manufacture of disposableabsorbent articles, including diapers, adult incontinence products,sanitary napkins and the like.

Manufacturing processes are often required to provide discrete strips ofa material onto a continuous web, in such a way that the discrete websof material are spaced apart along the length of the continuous web.Features manufactured in this way include either elastic or non-elasticstrips: one example of an elastic strip is the elastic leg cuffs appliedto diapers; one example of a non-elastic strip is the absorbent core ofa diaper or sanitary napkin which is typically constructed from air-laidfibres.

It is known to provide an apparatus for applying discrete portions of aweb material onto a receiving web by supplying elastic strips totransfer members in a supply zone, the transfer members being rotatedabout a central axis. The transfer members are moved radially outwardlyand then, in a transfer zone, the elastic strips are applied to thereceiving web so that the elastic strips are transferred from thetransfer members and onto the receiving web.

U.S. Pat. No. 4,578,133, issued Mar. 25, 1986, discloses a method andapparatus for applying elastic strips to a moving web of material bymeans of transfer members which move at a first orbital radius throughthe supply zone and at a second orbital radius through the transferzone. Optionally the transfer-members may also be radially pivoted bypivoting the transfer member about an axis transverse to its stripcarrying surface.

However, when the apparatus of the prior art are operated at high speedthe contact between the transfer elements, the elastic strips and thereceiving web occurs over a very brief period of time, usually no morethen several milliseconds. This results in difficulties in achieve goodreliable transfer of the strips from the transfer elements on to thereceiving web.

It is an objective of the present invention to provide an apparatuswherein the contact time between the transfer elements, the elasticstrips and the receiving web is increased.

SUMMARY OF THE INVENTION

The invention provides an apparatus for applying discrete portions of aweb material onto a receiving web, comprising:

a primary axis of rotation and an attachment zone at an average radialdistance, R₁, from the primary axis of rotation;

transfer elements rotatable about the primary axis, the transferelements receiving a second web at a radial distance, R₂, from theprimary axis wherein the radial distance R₁ is greater than the radialdistance R₂;

a means for displacing the transfer elements so that the second web ismoved immediately adjacent to the attachment zone; and

an attachment surface rotatable about the primary axis and through theattachment zone, for transporting the receiving web about the primaryaxis, whereby discrete portions of the second web is attached to thereceiving web in the attachment zone, forming a composite web comprisingthe receiving web and discrete portions of the second web.

The invention further provides a process for applying discrete portionsof a web material onto a receiving web, comprising the steps of:

providing an attachment zone at an average radial distance, R₁, from aprimary axis of rotation;

providing a second web at a distance, R₂, from the primary axis, wherebythe radial distance R₁ is greater than the radial distance R₂;

displacing the second web at least in a radial direction relative to theprimary axis so that the second web is displaced immediately adjacent tothe attachment zone;

juxtaposing the receiving web and the second web in the attachment zoneto form a composite web comprising the receiving web and discreteportions of the second web; and

transporting the receiving web about an arc of a circle, the circlehaving a primary axis and a first radius R₁.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of an apparatus according to the presentinvention in which the secondary web is translated through 180° about asecondary axis.

FIG. 2 shows a schematic plan view of the apparatus of FIG. 1.

FIG. 3 shows a schematic side view of a mechanism in cross-section whichis suitable for the apparatus embodied in FIG. 1.

FIG. 4 shows a perspective view of an apparatus according to anotherembodiment of the present invention in which the secondary web istranslated through 90° about the secondary axis.

FIG. 5 shows a perspective view of an apparatus according to stillanother embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

It will be readily apparent to those skilled in the art that althoughthe following description of the present invention is in connection witha single use diaper structure having discrete elastic regions or strips,the present invention may be practiced with equal facility on nearly anyweb.

It is preferred that the receiving web is a continuous web throughoutthe process of the present invention. In the following description a“continuous web” is a web of material which is continuous in the machinedirection. A preferred continuous web comprises a plurality ofinterconnected single use disposable absorbent articles, such asdiapers. Typically, each diaper is comprised of an absorbent pad elementor absorbent core, and elastomeric elements or patches. The absorbentpad elements and the elastomeric elements are located between abacksheet and a topsheet, or alternatively, on top of a backsheet ortopsheet. The continuous webs of backsheet material and topsheetmaterial are preferably maintained under very slight tension in themachine direction to prevent wrinkling and to facilitate registrationwith the diaper assembly and converting operations until the completeddiaper web is severed into discrete diapers by cutting across the widthof the web. An alternative single use disposable absorbent article is asanitary napkin or feminine hygiene pad.

The apparatus and process of the present invention provide a means forattaching discrete portions of one web onto a continuous receiving web.The discrete portions are intermittently spaced upon the receiving webby the apparatus and process of the present invention. The apparatus andprocess of the present invention provide “area contact” instead of “linecontact” to the receiving web to transfer the discrete portions ofanother web material. This gives much longer process times to secure thediscrete portions onto the receiving web. Moreover, it avoids extrusioneffects either of the discrete portions or of the receiving web, whichis important if they are soft and/or thick.

Another advantage of the apparatus of the present invention is in thefact that the discrete portions of web material and the receiving webare bent or shaped the same way when they are combined. This hasadvantages for several products, e.g. the combining step of femininehygiene pads should be done such that the products are directlymanufactured to the required body shape.

Preferably, the apparatus comprise a means for displacing the second webwhich comprises a plurality of segments, each segment being rotatableabout a secondary axis wherein the secondary axis is orthogonal to theprimary axis and does not intersect with the primary axis.

Even more preferably each rotatable segment receives a discrete portionof the second web, and the segment then rotates about the secondary axisthrough at least about 90°, and most preferably through about 180°, andjuxtaposes the discrete portion of the second web against the receivingweb in the attachment zone.

FIGS. 1 to 3 illustrate a preferred embodiment of the present invention.

FIGS. 1 and 2 show an apparatus 1 and show a pair of webs 2 being fedinto the apparatus. Each web 2 is fed towards an anvil drum 4 which, inthis particular embodiment of the apparatus, is a hexagonal drum. Theanvil drum comprises a plurality of anvils 5 (in this particularembodiment the hexagonal anvil drum 4 comprises six anvils 5). At thepoint of transfer of the incoming web 2 to the anvil drum 4, a transferelement 6 is interposed between the incoming web 2 and the anvil drum 4,and the incoming web is attached to the transfer-element 6 and cut intodiscrete portions 10 by a knife roll 3 acting against the anvil 5. Asthe anvil drum 4 is rotated about the primary axis of the apparatus, thetransfer elements 6 are displaced by additionally rotating the transferelements about a secondary axis, A—A. After a rotation of the transferelement 6 through 180° (which corresponds in the illustrated embodimentof FIG. 1 to a rotation of the anvil 4 about the primary axis of about140°), the transfer element 6 is juxtaposed with a receiving web 7 in anattachment zone. The receiving web 7 is continuously fed onto the outersurface 11 of a hexagonal attachment drum 12. In the attachment zone thediscrete portions 10 of the web 2 are transferred to, and attached to,the receiving web assisted by pressure applied between the transferelement 6 and the surface 10 attachment drum 12. As the apparatus 1continues to rotate about the primary axis, the transfer element 6rotates about the secondary axis in the opposite direction to theprevious part of the cycle, so that after a rotation of 180° thetransfer element 6 has returned to its original position and isinterposed between the anvil 4 and the incoming web 2. The cycle is nowready to repeat.

FIGS. 1 and 2 illustrate a hexagonal anvil drum 4, a hexagonalattachment drum 12, and six pairs of transfer elements 6. Of course theapparatus, could equally well consist of an octagonal anvil drum, andoctagonal attachment drum, and eight pairs of transfer elements; or anyother desired number of transfer elements. Furthermore, whilst FIG. 1shows pairs of transfer elements 6 disposed on either side of theapparatus 1, the apparatus 1 may only be fitted with one set of transferelements 6 on one side of the apparatus 1.

FIG. 3 shows a cross section of an apparatus 1 according to the presentinvention. The attachment drum 12 rotates about the primary axis of theapparatus 1. A cam 31 is mounted within the attachment drum 12 to guidean oscillating mechanism 32 which is provided with a rack 33. The rackcooperates with a pinion 34 which is linked to the pivotally mountedtransfer element 6. When the oscillating mechanism 32 is in the positionindicated in the lower part of FIG. 3, the transfer elements 6 are inposition ready to receive the incoming-web 2 at an average radialdistance R₂ from the principal axis. Knife rolls 3 cut the web 2 intodiscrete portions. As the apparatus 1 rotates about the principal axis,the oscillating mechanism 32 is pushed inwards, towards from theprincipal axis, by means of resilient members, such as springs 35. Therack and pinion 33, 34 cause the transfer elements 6 to rotate about asecondary axis. When the oscillating mechanism 32 is in the positionindicated in the upper part of FIG. 3, the transfer elements 6 havemoved through 180° about the secondary axis into the attachment zone andthe discrete portions of the web are transferred to the receiving web onthe outer surface 11 of the attachment drum 12 at an average radialdistance R₁ from the principal axis.

FIGS. 4 and 5 illustrate alternative embodiments of the presentinvention.

FIG. 4 shows an apparatus 41 according to an alternative embodiment ofthe present invention. FIG. 4 shows a pair of webs 42 being fed into theapparatus. Each web 42 is fed towards an anvil 44 which, in thisparticular embodiment of the apparatus, is a ten-sided drum. At thepoint of transfer of the incoming web 42 to the anvil 44, a transferelement 46 is interposed between the incoming web 42 and the anvil 44,and the incoming web is attached to the transfer element 46 and cut intodiscrete portions by a knife roll 43 acting against the anvil 45. As theanvil drum 44 is rotated about the primary axis, the transfer elements46 are displaced by additionally rotating the transfer elements about asecondary axis. After a rotation of the transfer element 46 through 90°(which corresponds in the illustrated embodiment of FIG. 4 to a rotationof the anvil 44 about the primary axis of about 140°), the transferelement 46 is juxtaposed with a receiving web 47 in an attachment zone.The receiving web 47 is continuously fed onto the flange of anattachment drum 49. In order to accommodate the linear receiving web 47around the circular path of the flange 49 of the attachment drum, aseries of “hold-down” sections and compensation triangles are providedas illustrated in FIG. 4. In the attachment zone the discrete portionsof the web 42 are transferred to, and attached to, the “hold-down”section of the receiving web 47 assisted by pressure applied between thetransfer element 46 and the flange 49 of the attachment drum. As theapparatus 41 continues to rotate about the primary axis, the transferelement 46 rotates about the secondary axis in the opposite direction tothe previous part of the cycle, so that after a rotation of 90° aboutthe secondary axis the transfer element 46 has returned to its originalposition and is interposed between the anvil 44 and the incoming web 42.The cycle is now ready to repeat.

FIG. 5 shows an apparatus 51 according to another alternative embodimentof the present invention. FIG. 5 shows a of web 52 being fed into theapparatus. The web 52 is fed towards an anvil drum 54. At the point oftransfer of the incoming web 52 to the anvil 54, a transfer element 56is interposed between the incoming web 52 and the anvil 54 the incomingweb is attached to the transfer element 56 and cut into discreteportions by a knife roll 53 acting against the anvil 55. As the anvildrum 55 is rotated about the primary axis, the transfer elements 56 aredisplaced both parallel to the primary axis as well as radially awayfrom the primary axis, the displacement being indicated by arrows inFIG. 5, into an attachment zone. The attachment zones lie in a series ofapertures in the outer surface of the attachment drum 59. The discreteportions of the web 52 are bonded to the receiving web 57 by means ofpressure applied by a bonding roll 58 located outside of the path of thereceiving web 57, acting upon the displaced transfer element 6. Thetransfer elements 56 are subsequently displaced back to their originalposition so that the cycle can be repeated.

In an optional aspect of the invention, glue can be applied either tothe knives or to the anvil of any embodiment of the invention, beforethe second web is cut into discrete portions. When the second web is cutinto discrete portions, glue is transferred to the ends of the discreteportions which provides for efficient sealing of the cut ends of thediscrete portions with a very small amount of glue.

What is claimed is:
 1. A process for applying discrete portions (10) ofa web material onto a receiving web (7), comprising the steps of:providing an attachment zone at an average radial distance, R₁, from aprimary axis of rotation; providing a second web (2) at a distance, R₂,from the primary axis, whereby the radial distance R₁ is greater thanthe radial distance R₂; displacing the second web (2) at least in aradial direction relative to the primary axis so that the second web (2)is displaced immediately adjacent to the attachment zone; juxtaposingthe receiving web (7) and the second web (2) in the attachment zone toform a composite web comprising the receiving web (7) and discreteportions (10) of the second web (2), wherein discrete portions (10) areformed by cutting the second web (2); characterised in that the processfurther comprises the step of transporting the receiving web about apath lying essentially in the arc of a circle, the essentially circularpath at radius R₁ from the primary axis of rotation, wherein the entirediscrete portions (10) of the second web (2) are displaced in an axialdirection, in addition to the translation in the radial direction,relative to the primary axis.
 2. A process according to claim 1 whereinthe discrete portions (10) of the second web (2) are displaced about asecondary axis, wherein the secondary axis is orthogonal to the primaryaxis and does not intersect with the primary axis.
 3. A processaccording to claim 2 wherein the discrete portions (10) of the secondweb (2) are translated through at least about 90° about the secondaryaxis.
 4. A process according to claim 1 wherein the cutting step iscarried out by means of the action of a knife upon an anvil, and whereinthe surface of either or both of the knife and anvil have glue appliedto them before the cutting step.
 5. An apparatus (1) for applyingdiscrete portions (10) of a web material onto a receiving web (7),comprising: a primary axis of rotation and an attachment zone at anaverage radial distance, R₁, from the primary axis of rotation; transferelements (6) rotatable about the primary axis, the transfer elementsreceiving a second web (2) at a radial distance, R₂, from the primaryaxis wherein the radial distance R₁ is greater than the radial distanceR₂; a means for displacing the transfer elements (6) so that the secondweb (2) is moved immediately adjacent to the attachment zone; a means(3, 5) for cutting the second web (2) into discrete portions (10);characterised in that the apparatus further comprises an attachmentsurface (10) rotatable about the primary axis and through the attachmentzone, for transporting the receiving web (7) about the primary axis,whereby discrete portions (10) of the second web (2) are attached to thereceiving web (7) on the attachment zone, forming a composite webcomprising the receiving web (7) and discrete portions (10) of thesecond web (2), wherein the average radial distance, R₁, issubstantially the same over the entire attachment surface.
 6. Anapparatus according to claim 5 wherein the means for displacing thesecond web (2) comprises a plurality of segments, each segment beingrotatable about a secondary axis wherein the secondary axis isorthogonal to the primary axis and does not intersect with the primaryaxis.
 7. An apparatus according to claim 6 wherein each rotatablesegment receives a discrete portion (10) of the second web (2), andwherein in segment rotates about the secondary axis through at leastabout 90°, and juxtaposes the discrete portion (10) of the second web(2) against the receiving web (7) in the attachment zone.